Add Chrome OS's minigbm library to third_party

DEPS

 # This file is used to manage the dependencies of the Chromium src repo. It is
 # used by gclient to determine what version of each dependency to check out, and
 # where.
 #
 # For more information, please refer to the official documentation:
 #   https://sites.google.com/a/chromium.org/dev/developers/how-tos/get-the-code
 #
 # When adding a new dependency, please update the top-level .gitignore file
 # to list the dependency's destination directory.
 #
@@ skipping 395 matching lines @@
     'src/third_party/liblouis/src':
      Var('chromium_git') + '/external/liblouis-github.git' + '@' + '5f9c03f2a3478561deb6ae4798175094be8a26c2',
 
     # Used for embedded builds. CrOS & Linux use the system version.
     'src/third_party/fontconfig/src':
      Var('chromium_git') + '/external/fontconfig.git' + '@' + 'f16c3118e25546c1b749f9823c51827a60aeb5c1',
 
     # ANGLE uses dEQP for GPU testing
     'src/third_party/deqp/src':
      Var('deqp_url') + '@' + Var('deqp_revision'),
+
+    # Graphics buffer allocator for Chrome OS.
+    'src/third_party/minigbm/src':
+     Var('chromium_git') + '/chromiumos/platform/minigbm.git' + '@' + 'f9d2ab79a15a1bb6a1307f3b608964c81c27791b',
   },
   'android': {
     'src/third_party/android_protobuf/src':
      Var('chromium_git') + '/external/android_protobuf.git' + '@' + '999188d0dc72e97f7fe08bb756958a2cf090f4e7',
 
     'src/third_party/android_tools':
      Var('chromium_git') + '/android_tools.git' + '@' + '4238a28593b7e6178c95431f91ca8c24e45fa7eb',
 
     'src/third_party/apache-mime4j':
      Var('chromium_git') + '/chromium/deps/apache-mime4j.git' + '@' + '28cb1108bff4b6cf0a2e86ff58b3d025934ebe3a',
@@ skipping 373 matching lines @@
     # migration completes (let's say Sep 1 2014).
     'name': 'check_git_config',
     'pattern': '.',
     'action': [
         'python',
         'src/tools/check_git_config.py',
         '--running-as-hook',
     ],
   },
 ]